Simultaneous Achievement of Enhanced Dielectric Energy Storage Performance and Ultrahigh Hardness in BaTiO ₃ ‐Based Glass Ceramics via Vortex‐Domain Engineering

ABSTRACT Glass ceramics are supposed to offer the potential of retaining the high permittivity of ceramics, and at the same time exhibiting high dielectric breakdown strength (DBS), thus producing high dielectric energy storage performance in bulk material. Nonetheless, to date, it still remains a big challenge to achieve high energy storage density in glass ceramics compared to other dielectric energy storage materials. Herein, we conceived and fabricated a new type of BaTiO 3 ‐based glass ceramics with nanoscale polymorphic structure in a single nano‐grain formed by Ge‐ions simultaneous substitution of A and B sites during crystallization. It has been found that appropriate GeO 2 doping concentration will form nanoscale spontaneous polarization vortex domains in a single nano‐grain, which enhances polarization, efficiency, and DBS. As a result, excellent energy storage performance is achieved, with a high recoverable energy density (W rec ) of 10.08 J cm −3 with high energy storage efficiency of 91.3% and high charge–discharge energy storage density (W d ) of 8.84 J cm −3 under 1500 kV cm −1 . It also exhibits ultrahigh hardness (10.2 GPa). This work shows the potential applications of BaTiO 3 ‐based glass ceramics in high and pulsed power devices and provides a strategy for designing advanced dielectric glass ceramics.